Porcine epidemic diarrhea virus (PEDV) is a coronavirus that causes serious and highly contagious

enteric disease in swine worldwide. In this study, we constructed a recombinant baculovirus

(S-Bac) expressing full-length spike protein of the virulent epidemic genotype 2b (G2b) PEDV strain

for serological studies of infected pigs. We found that most spike-specific antibodies produced

upon PEDV infection in pigs are conformation-specific and they could be detected on S-Bac-infected

insect cells by immunofluorescent assay, but they were insensitive to Western blot analysis, the

typical method for antiserum analysis. These results indicated that spike conformation is crucial for

serum recognition. Since it is difficult to purify trimeric spike membrane protein for conventional

enzyme-linked immunosorbent assay (ELISA), we used S-Bac to generate a novel cell-based ELISA

for convenient PEDV detection. We analyzed 100 pig serum samples, and our cell-based ELISA

exhibited a sensitivity of 100%, a specificity of 97%, and almost perfect agreement [Cohen’s kappa

coefficient value () = 0.98] with immunocytochemical staining results. Our cell-based ELISA rapidly

presented antigen for proper detection of conformation-specific antibodies, making PEDV detection

more convenient, and it will be useful for detecting many viral diseases in the future.